-9r^2-8r-1=r-r^2-9

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Solution for -9r^2-8r-1=r-r^2-9 equation:


Simplifying
-9r2 + -8r + -1 = r + -1r2 + -9

Reorder the terms:
-1 + -8r + -9r2 = r + -1r2 + -9

Reorder the terms:
-1 + -8r + -9r2 = -9 + r + -1r2

Solving
-1 + -8r + -9r2 = -9 + r + -1r2

Solving for variable 'r'.

Reorder the terms:
-1 + 9 + -8r + -1r + -9r2 + r2 = -9 + r + -1r2 + 9 + -1r + r2

Combine like terms: -1 + 9 = 8
8 + -8r + -1r + -9r2 + r2 = -9 + r + -1r2 + 9 + -1r + r2

Combine like terms: -8r + -1r = -9r
8 + -9r + -9r2 + r2 = -9 + r + -1r2 + 9 + -1r + r2

Combine like terms: -9r2 + r2 = -8r2
8 + -9r + -8r2 = -9 + r + -1r2 + 9 + -1r + r2

Reorder the terms:
8 + -9r + -8r2 = -9 + 9 + r + -1r + -1r2 + r2

Combine like terms: -9 + 9 = 0
8 + -9r + -8r2 = 0 + r + -1r + -1r2 + r2
8 + -9r + -8r2 = r + -1r + -1r2 + r2

Combine like terms: r + -1r = 0
8 + -9r + -8r2 = 0 + -1r2 + r2
8 + -9r + -8r2 = -1r2 + r2

Combine like terms: -1r2 + r2 = 0
8 + -9r + -8r2 = 0

Begin completing the square.  Divide all terms by
-8 the coefficient of the squared term: 

Divide each side by '-8'.
-1 + 1.125r + r2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + 1.125r + 1 + r2 = 0 + 1

Reorder the terms:
-1 + 1 + 1.125r + r2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + 1.125r + r2 = 0 + 1
1.125r + r2 = 0 + 1

Combine like terms: 0 + 1 = 1
1.125r + r2 = 1

The r term is 1.125r.  Take half its coefficient (0.5625).
Square it (0.31640625) and add it to both sides.

Add '0.31640625' to each side of the equation.
1.125r + 0.31640625 + r2 = 1 + 0.31640625

Reorder the terms:
0.31640625 + 1.125r + r2 = 1 + 0.31640625

Combine like terms: 1 + 0.31640625 = 1.31640625
0.31640625 + 1.125r + r2 = 1.31640625

Factor a perfect square on the left side:
(r + 0.5625)(r + 0.5625) = 1.31640625

Calculate the square root of the right side: 1.147347484

Break this problem into two subproblems by setting 
(r + 0.5625) equal to 1.147347484 and -1.147347484.

Subproblem 1

r + 0.5625 = 1.147347484 Simplifying r + 0.5625 = 1.147347484 Reorder the terms: 0.5625 + r = 1.147347484 Solving 0.5625 + r = 1.147347484 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.5625' to each side of the equation. 0.5625 + -0.5625 + r = 1.147347484 + -0.5625 Combine like terms: 0.5625 + -0.5625 = 0.0000 0.0000 + r = 1.147347484 + -0.5625 r = 1.147347484 + -0.5625 Combine like terms: 1.147347484 + -0.5625 = 0.584847484 r = 0.584847484 Simplifying r = 0.584847484

Subproblem 2

r + 0.5625 = -1.147347484 Simplifying r + 0.5625 = -1.147347484 Reorder the terms: 0.5625 + r = -1.147347484 Solving 0.5625 + r = -1.147347484 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.5625' to each side of the equation. 0.5625 + -0.5625 + r = -1.147347484 + -0.5625 Combine like terms: 0.5625 + -0.5625 = 0.0000 0.0000 + r = -1.147347484 + -0.5625 r = -1.147347484 + -0.5625 Combine like terms: -1.147347484 + -0.5625 = -1.709847484 r = -1.709847484 Simplifying r = -1.709847484

Solution

The solution to the problem is based on the solutions from the subproblems. r = {0.584847484, -1.709847484}

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